This project deals with electroretinogram recordings from schizophrenic patients while on haloperidol therapy and then following a six-week drug-free period. Comparisons are always made between the same eye in the two conditions for a given patient. Thus, the influence of dopaminergic blockers on electrically discrete photoreceptor systems can be evaluated. In addition to the relative data comparison, the results will also be analyzed with respect to normal volunteer data matched for age and sex.